Electrical heating device



July 5, 1932 J. H. GAI-:TJE ET AL 1,866,097

` ELECTRICAL HEATING DEVICE v Fned may 14, 1929 a Anzi/1 PW July s. 1932 yUNITI-:o STAT-as.

PATENT" oFFica l JOHN HERMAN GAETJ'EfOF GLNV'IEW, .AND ARTHUR EDWIN SAN'I'BCHI. 0F CHICAGO,

ILLINOIS, ASSIGNOBS TO WESTERN ELECTRIC COMPANY, INCORPORATED, YORK., N. Y., .L CORPORATION OI NEW YORK Y or Naw ELEGI'BICAL HEATING DEVICE Anuman ma any i4,

This invention relates to electrical heating' devices, andl more particularly to electrical heating' devices.. for heating 'and melting metal and metallic alloys and maintaining them in the molten state.

In the heating and meltin of lead alloyin an extruding press for, sheaiing telephone cable with' a lead covering it is desirable that the entire lead containing portion of the press be maintained at a uniform temperature, and the preferable way or producing this uniform tem rature is to attach individual heating units to various external portions of the press especially to those ortions which are somewhat removed from t e main Y body thereof.

An object of this invention is t0 provide an eilicient and economical heating device shaped to accuratel fit a body to be heated.

In accor ance with this object one embodiment of the invention consists of a resistance element which is embedded within a plastic, quick-setting refractory cement incased With- -in a metal box and positioned therein by Y means of highly' refractory insulating bridges. l Ample -size terminal rods to withstand a high degree of heat extend through a wall of the box and are brazed to the resistc ance element on the inside. An external com# partment filled with the plastic cement protects Ithe connections of the terminal rods Vwith their leads. n

A clear understanding of the invention will be had from the following description of one specific embodiment thereof when taken in connection vwith the accompanying drawing, wherein v Fig. 1 is a plan and partly sectional view of the heating device with its cover and most lof the embedding cement removed; and

Fig. 2 is a sectional view of the` same device including the cover, which is taken on the line 2-2 of Fig. 1.

Referring now tothe drawing in which like figures, the numeral 5 denotes a heavily constructed metallic box which may be constructed or shaped into any desired form according to the surface to which it is ap lied and which 5 is capable of withstanding t e temperature numerals designate similar parts in thetwo icas. serial no. acaaio. Q provided in this invention for fusing metal, which box is preferably composed o aluminum bronze forthis purpose. The walls and bottom of the box are comparatively thick to provide a large mass of metal and the external surface of the bottom' is machined or planed for making a continuous intimate contact with the surface of the metal container or other body against 'which the bottom'is ap plied, thereby avoiding air pockets or spaces means for fastening the box to the body to be heated. Although only one .boss is shown and 'the box 5 happens to be -rectangular in this case, it will be understood that the boi.' may take various shapes, dependingl upon theh shape of the body to which it is applied, and thenumber of such bosses may also vary.

Inside of the box 5 are placed a plurality of suitably spaced, highly refractory insulating bridges, sitioning a heatingwor resistance element therein. The bridges 7 are composed of a suitable refractory material, preferably fired lavite, which is a very compact, homogeneous insulating minerali' A plurality of corresponding, transverse apertures 8 extend through the bridges 7 at spaced intervals, and downwardly sloping slots 9 aie provided to lead into the apertures 8 for a purpose which will presently appear.

A heating element in coil form l0 consisting of any suitable resistance metal for main taining'a relatively high temperature, such as nickel-chromium Wire, is'threaded longitudinally through the apertures 8 of the lavite bridges 7 before the bridges are placed inside the box, thus forming one continuous serpentine-shaped heating element extend ing from a terminal 11 tok a terminal 12. The resistance coil 10 and its bridges 7 are placed in the box 5 and the terminals 11 and 12 are connected to terminal rods 13 of a relatively large cross-section,preferably by brazing. The terminal rods 13 being of or supports 7 for the purpose of polarge cross-section conduct heat away from these connections and thus provide connections which will successfully withstand the heat. The-terminal rods 13 extend through 5 a wall of the box 5 and are insulated therefrom by bushings 14, and a tubular porcelain insulator surrounds the longer terminal rod 13 to prevent it from contacting with the l box and the coil. 10 Over and around the positioning bridges 7 is deposited a plastic, quick-acting, re ractory cement 18, preferably alundum cement,

for embedding or enveloping the entire coil 10 and securing the bridges 7 in fixed position in the box. The alundum cement 18 is forced down into `each of the transverse apertures 8 of the bridges 7 by way of the sloping slots 9 for 4the purpose of surrounding each turn of the coil 10 and insulating the turns of the coil from each other, and also toprevent any air spaces appearing adjacent the coil. Thus the cement 18 not only incases the portions of the coil which are unsupported by the bridges, but embeds the coil portions disposed within the bridges as well. The entire unfilled space of the box 5 up to the top level thereof is filled with this cement, and

care is taken to see that the coil is insulated from the boss 6. A sheet metal cover 19 retained by screws threaded into apertures 20 protects the upper surface of the cement from external interference and secures it within the box.4

The external ends of the terminal rods 13 have asbestos covered leads 21 soldered thereto, as shown at 22, and surrounding these soldered connections are wound asbestos cords 23 for protecting the soldered connections against the heat.' A metallic shield 4o or housing 24 suitably secured to the box 5 and filled with the alundum cement 18 also surrounds and protects these external connections and prevents the terminal rods 13 from becoming short circuited by overflowing or leaking molten metal from the container being heated. i

This completes the description of this readily constructed heating device which may be easily made in various forms or shapes for fitting divers parts of metal fusing apparatus or lead sheathing presses. TheV fused lavite bridges serve to position a heating ele ment in anyshape of box, while the alundum cement seals and embeds the heating element in that position, and the heat is eiciently conducted through the lavite bridges and the machined bottom .of the box into the wall of the metal container or other body being heated. The alundum cement may be used without the lavite bridges and provides for mounting of the heating element adjacent various shapes of depresslons or cavities external of the metal container, but it is preferable to use the lavite brid for ment. It is, there ore, to understood that ositioning the ele the heating device herein disclosed is economical to construct and subject` to a variety of readily constructed sha l' It will be understood, o course, that the invention is not to be limited .to the specific structure herein disclosed and illustrated, but it is to be limited only by the-scope of the appended claims.

What 'is claimed is: f Y

1. In an electrical heating device, a casing, a resistance element, means whereby said resistance element may be disposed in zigza arrangement in said casing and held in p ace, said means comprising a pluralit of bridges having aligned recesses therein through which said resistance element may be threaded and held in place by the walls thereof, a refractory material disposed in said casing and in said recesses for surrounding and embedding said resistance element and said bridges, a cover for said casing, and a tubular extension integral with the casing extending through the refractory material to the cover.

2. In an electrical heating device, a casing, a resistance element, means whereby said resistance element may be disposed in zigzag arrangement in said casing and held in place, said means comprising aplurality of bridges having aligned recesses therein through which said resistance element may be threaded and held in place by the walls thereof, a refractory material disposed in said casing and in said recesses for surrounding and embedding said resistance element and said bridges, and a cylindrical boss extendin through said casing and spaced from sai resistance element whereby said casing may be secured in a receptable.

In witness whereof, we hereunto subscribe our names this 30th day of April, A. D.1929.

' JOHN HERMAN GAETJE. ARTHUR EDWIN SANTSCHI. 

